Foaming cosmetic compositions for personal cleansing and cosmetic purposes must satisfy a number of criteria including good cleansing power and foaming properties.
Ideal cosmetic cleansers should cleanse the skin or hair gently, without causing irritation, without dehydrating the skin, and without leaving the skin feeling taut after use. Ideal cosmetic cleansers should also condition the skin. Most lathering soaps, liquids, gels and bars fail in one or more of these respects.
For example, good foaming cleansers tend to be harsh to the skin. This occurs because the surfactant systems that provide good lathering performance, while being effective cleansers, also tend to dehydrate the skin and remove lipids from the skin. The skin becomes dry due to the hygroscopic effect of the surfactants, which remove water from the skin. The skin becomes tight, or taut due to the emulsification effects of the surfactants. The surfactants emulsify natural oils in the skin, which are then washed away when the cleansing composition is rinsed off.
Humectants are conditioning materials known in the skin care art for rehydrating skin and aiding in retention of water by the skin. Emollients are conditioning materials known in the art for remoisturizing the skin or hair with lipids or other oils or oily materials. However both of these types of conditioners are difficult to formulate into a lather-producing or foam-producing product. Mere addition of conventional conditioning agents, such as emollients and humectants, interfere with the lather forming ability of the surfactant. This is undesirable because consumers often associate foam and lather with cleansing ability, and tend to prefer foam or lather producing products for aesthetic reasons as well. Furthermore, the use of high-sudsing surfactants tends to be unduly harsh to the skin and occular tissue, even with the addition of conditioning ingredients. The use of milder surfactants can reduce adverse effects on the skin, but these surfactants generally have poor lather and foaming ability. The addition of skin conditioning components can further improve the skin mildness of these surfactants, but would further degrade foaming and lathering of an already poorly foaming and lathering composition.
Products that are highly effective for conditioning the skin are generally either non-cleansing or low-cleansing compositions, or if they cleanse, they do not provide high quality lather or foam. An example of this latter type of skin cleanser is an emollient cleanser. Emollient cleansers are typically creams which do not provide foam or lather.
Thus a need exists for cosmetic compositions which will produce a foam or lather which is abundant, stable and of high quality and compactness, which are effective cleansers, and yet which are very mild to the skin, hair and preferably occular mucosae, and further which can condition the skin. In particular, it is desirable to provide such a product which contains both emollients and humectants which are effective for remoisturizing and inhibiting dehydration of the skin.
One solution to this problem of achieving good foaming and cleansing characteristics without sacrificing mildness has been to deliver low foaming, mild surfactant compositions as a pre-foamed product. However, to do this requires that the delivery be made from an aerosol container employ propellant gasses. In light of heightened environmental and safety concerns, it would be highly desirable to achieve such foaming compositions without the use of aerosol containers and propellant gasses. However, current non-aerosol squeeze and pump foaming devices are unable to conveniently deliver foams having highly desired foaming and cleansing properties. These nonaerosol delivered foams tend to be thin and runny. Also, conventional non-aerosol foamers are not practicable for delivering compositions having a viscosity much above about 50 cps, unless inconveniently high actuation forces are used to dispense the product. In other words, consumers cannot conveniently dispense a viscous composition from a conventional non-aerosol foamer.
Further, known prior foam-producing, nonaersol products still do not combine all the essential properties of an ideal product--i.e., good foam or lathering properties; effective cleansing; mildness; and conditioning, including both effective delivery of emollients and humectants; and delivery of a high quality foam from a non-areosol dispenser that is convenient for personal use. It is therefore an object of this invention to provide such a product.
In order to provide high quality lather or foam, conventional skin cleansing products based on surfactant cleansers typically contain from greater than 10% to about 20% of surfactants, typically including relatively high levels of anionic surfactants. Lather is produced as a result of physical agitation, e.g. rubbing with ones hands or mechanical devises (e.g., sponges and washcloths), on the skin. The high levels of surfactants used in these products have substantial dehydration and delipidization effects on the skin. Even products that contain humectants and emollients to compensate for this typically are not completely effective at restoring the skin to its original condition. It would be desirable to provide a foaming cleansing product which could restore the skin to its original levels of hydration and lipids. It is an additional object of this invention to provide such a product.
It would be further desirable to provide a foaming cleansing product which could provide effective cleansing and high quality foam and which could increase the level of hydration and/or lipid content at the skin surface upon use. It is yet another object of this invention to provide such a product.
These and other objects will become readily apparent from the detailed description which follows.